An echocardiogram (often called "echo") is a graphic outline of the heart's movement, valves and chambers . During the transesophageal echocardiogram (TEE) test, an ultrasound transducer (which produces high frequency sound waves) provides pictures of the heart's valves and chambers and helps the physician evaluate the pumping action of the heart.
The ultrasound transducer is positioned on an endoscope (a long, thin, flexible instrument about 1/2 inch in diameter). The endoscope is placed into your mouth and passed into your esophagus (the "food pipe" leading from your mouth into your stomach) to provide a close look at your heart's valves and chambers without interference from the ribs or lungs.
TEE is often combined with Doppler ultrasound and color Doppler to evaluate blood flow across the heart’s valves. TEE is often used when the results from standard echo studies were not sufficient or when your doctor wants a closer look at your heart.